Double-lift jack



J uly M. B. LUCKER DOUBLE LIFT JACK Filed July 2O I 1925 Patented duly 20, 1926.

tsaar? MILLAR-D B. LUCKER, F BENTON HARBOR, MICHIGAN, ASSIGNOR 'E0 AUTO SPE- CIALTIES MFG. C0., OF SAN FRANCISCO, CALIFORNKA, A CORPORATION OF CALI- FORNIA.

DOUBLE-LIFT LACK Application :tiled July 20,

rllhis invention relates to lifting jacks for heavy loads and particularly to those of the double lift type which can be collapsed into an extremely small compass for transportation and storage in an automobile or the like.

The invention consists in mechanism for attaining the foregoing andother objects hereinafter more fully set forth in the specification and claims.

Referring to the drawings in which like numerals refer to the same parts throughout the several views:

Figure 1 is a plan view taken in section on the line 1-1 of Figure 2.

Figure 2 is a central, sectional side elevation of the mechanism of Figure 1, showing the parts in collapsed position.

Figure 3 is a view similar to Figure 1, showing the jack extended to its maximum loa d carrying capacity.

ln the preferred form of the mechanism, shown 1n tht drawings, a retaining base is provided comprising an upstanding, hollow portion 1 0 open at its top and communicating at its bottom with a horizontal case membei' 12, liaving in it a recess 14 for the reception of the main driving gear 16 of the jack. The gear chamber 14 is closed by a bottom plate 17 detachably secured in place as shown by any suitable means as, for instance, the screws 18. The two base portions 1() and 12 are braced at four points 90 apart by east webs 2O of conventional form with the result that the case as a whole is amply able to withstand all load strains which may be imposed upon it.

Horizontal gear 16. heretofore referred to, is journaled in chamber 14 on bottom rplate 17 by any conventional form of anti-friction mechanism, specifically ball-bearing devices 22 of Figure 2 of the drawings. Beveled gear 16 is driven by a beveled pinion 24 inter-meshing with it, so placed that its hub 26 extends outside the base at a convenient angle to be engaged by a suitable driving instrument. The driving instrument may be either a. long augerlike handle, having its lower, non-circular end fitable into a noncircular socket 28 in the shaft 26, or it may be a suitable tool applied to irregular surfaced wheel or gear 30, rigidly secured to the outside of shaft 26. Shaft 26 is journaled 1925. Serial No. 44,818.

in a suitable bearing formed in the exterior of thecase. Pinion 24 rotates in a recessed chamber 34, provided for it at one side of the base, and in communication with chamber 14, heretofore described, all as clearly appears in Figure 2.

Horizontal gear 16 is rigidly secured by any suitable means not detailed in the drawings, to ashort, comparatively small lifting screw 36. Fitting over screw 36 and in screw threaded engagement therewith is a second, larger screw 38, screw threaded inside and out. The internal threads 40 formed upon the lower end of screw member 88 extend only a. short distance into the interior chamber 42 of said screw member. Screw 36 is provided with a, transverse pin 44 above the screw threads 40 of screw member 38 which engages the tops of the screw threads 40 if the screw 38 is moved any higher than shown in the 'position of Figure 3, with the result that rotation of screw 86 cannot drive large screw member 38 olf from the top of said screw member 36.

In similar manner,l the external screw threads of screw member 38 operatively engage internal screw threads 46 extending for a short distance into the lower end of the upper rectangular slide or .load engaging member 48 of the jack which latter terminates at its upper end in the lload engaging block 50 of conventional form, `and similarly, the upper end of screw 38 is equipped with a transverse, horizontal pin 52 which engages the upper end of load carrying internal screw'threads 46 on slide 48 to prevent the slide being .accidentally removed from large screw 38.

The lower external surface of load carrying slide 48 is equipped with a protruding flange 54 which is in turn engageable with an internal flange on an intermediate hollow slide'mernber 58, said latter member being slidably engaged in the upstanding portion 10 of the base. .ln similar manner, the lower end of the slide member 58 has an eX- ternal ange 60 engageable with an internal flange 62 on the upper end of the upstanding portion 10 of the base.

The result of the' construction described is that engagement of flanges 60 and 62 prevents slide 58 being lifted upwardly out of case 10and the engagement of iianges 54 and 56 prevents the lifting of upper slide 48 out of intermediate slide 58.

It may be explained at this point that when it is necessary to separate the parts 10-58 and 48, it is accomplished by irst removing the plate 17 and then withdrawing the entire lifting mechanismout through the bottom of the case mechanism in quite obvious manner.

Inl the operation of the jack, assume the parts areln the position of Figure 2 and that the operating tool for rotating shaft 26 has been applied. Rotation of this shaft in the proper direction, depending on the character' of the threads of the jack, results iirst in the movement of the smaller or inside screw 23S-this because it is rigidly attached to gear 16 which is in mesh with pinion 24, rigid on shaft 26. As this screw 36 turns, it forces interitting screw threads 40 on large screw 38 to travel up screw 36 until such time as the upper ends of the screw threads engage pin 44. When this engagement takes place and screw 36 is further rotated, it carries large -screw 38 with it thereby necessarily rotating that screw and thus forcing screw threads 46 on upper slide 48 to travel up the outside threads of screw 38. lThis movement takes place until the threads on the inside of upper slide 48 encounter pin 52 whereupon further movement is prevented and the jack has reached its maximum vertical position. Rotating shaft 26 and pinion 24 in the opposite direction from that which was used in elevating the jack, results in the return of the parts from fully extended position of Figure 3 to contraeted position of Figure 2.

Attentionl is called to the fact that the entire load is carried upon the screws and not by the vertically disposed case member 10 and the intermediate slide 58, thereby insuring free, easy operation of the device.

In actual practice, the mechanism has been found most eiiicient and satisfactory, displacing numerous prior devices heretofore lin the market.

The use of the non-circular, specifically rectangular members 48-58 and 10 telescopically interitting has advantages particularly when the jack is without load on the member 50. However, any cross sectional parts including circle may be used without departing from the broad principle of the invention.

The members 44 and 52 are described as pins and may be, obviously7 protruding members of other character as, for instance,

welded stops, without departing from the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A jack comprising a hollow base having a vertical extension open at its top, a plurality of slidably telescoping members projectable and retractable from and into said extensiom a screw device mounted within the base for projecting and detracting said members, said device having direct connection solely with the innermost member whereby the latter is initially projected independently of the remainder of said members, means operable by continued projection of the innermost member beyond a predetermined point to successively project the remainder of the members, and means for limiting the projection of the outermost member with respect to said extension.

2. A jack comprising a hollow base having a vertical extension open at its top, a plurality of slidably telescoping members projectable and retractable from and into said extension, a screw device mounted within the base for projecting and retracting said members, said device having direct connection solely with the innermost member whereby the latter is initially projected independently of the remainder of said members, means separate from the screw device operable by continued projection of the innermost member beyond a predetermined point to successively project the remainder of the members, and means for limiting the projection of the outermost member with respect to said extension.

3. A jack comprising a hollow base having al vertical extension open at its top, a plurality of slidably telescoping members projectable and retractable from and into said extension, a screw device mounted within the base for projecting and retracting said members, said device having direct connection solely with the innermost mem` ber whereby the latter is initially projected independently of the remainder) of said members, cooperating stops on adjacent members whereby continued projection of the innermost member beyond a predetermined point will successively project the remainder of the members, and means for limiting the projection of the-outermost member with respect to said extension.

In witness whereof, I have hereunto subscribed my name.

MILLARD B. LUCKER. 

